|Evolution in the News - January 1997|
But if you read the December 14 issue of Science News (Ev-), you would come to a much different conclusion. That article says,
“Since August, everything I’ve seen--other people’s work and my own--has weakened their [NASA’s] proposal”, says planetary scientist John F. Kerridge of the University of California, San Diego. “Now I think they don’t have a shred of evidence to back it up.”
Then it describes work done by Harry Y. McSween Jr. of the University of Tennessee in Knoxville, and his colleagues, involving transmission electron microscopy. Their conclusion was that “closer inspection of the internal structure of the magnetite in ALH84001 revealed that it could not have been formed by a living organism.”
The skepticism that we expressed in the November issue of Disclosure seems to be more widely shared in scientific circles.
There is one paragraph in that Science News article that we want to particularly mention. It says,
Using different radioactive dating techniques, two independent research groups disagree on when ALH84001 acquired its carbonates. One team suggests that the carbonates were deposited some 3.6 billion years ago, when researchers believe Mars had an abundant supply of water. Another estimates that they were inserted about 1.4 billion years ago, by which time Mars’ water supply might have dwindled.
This paragraph points out the basic unreliability of radioactive dating of rocks. Radioactive dating often gives discordant ages. In the next issue of Disclosure, the feature essay will focus on the problems with radioactive dating. Then we will describe the various radioactive dating methods, the basic assumptions they make, and why these assumptions are likely to be wrong. We will give some examples from the literature showing how different the computed ages often are. For now, we just want to point out that the differences between 1.4 billion years, 3.6 billion years, and 4.5 billion years are not short time intervals, even to a geologist.
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